1. Field of the Invention
This invention relates to personal care products, and, more particularly, to a hair gel composition which is a blend of two polymers which together exhibit a synergistic rheological and viscosity effects on the composition, as well as providing advantageous fixative, curl retention, suspending and clarity properties.
2. Description of the Prior Art
Today""s consumer has a wide range of products available for hair care. This includes many product forms designed for styling such as mousses, hair sprays, setting lotions and hair gels. The popularity of hair gels makes them a significant portion of the hair care market. Essential to the acceptance of styling gels by consumers are aesthetics and performance. Attributes of aesthetic properties are clarity, color, odor, appearance, rheological behavior, and easy dispersing from a tube or jar. Performance attributes include high humidity curl retention, and hair characteristic qualities such as easy application, non-tacky feel, quick drying, no residue or flaking, increased hair body and volume, good gloss or shine, and in most cases not too excessively stiff. Another important consideration is easy removal by shampooing. So one can see that many factors go into play in the formulation of an acceptable and functional hair styling product.
A basic styling gel contains a good diluent. Most typically, the diluent consists of deionized water but it also may contain an alcohol, such as ethanol, although regulatory requirements have set an upper limit at 6.0% VOC for such products. The next most common ingredients in styling gels are the hair fixative polymers and the gelling or thickening system. In many cases a neutralizer also is required for the functionality of the gellant. Auxiliary ingredients normally include preservatives, UV absorbers to protect the product or UV sunscreens to protect the hair from sun damage, chelating agent, fragrance, color, and solubilizers such as nonionic surfactants. If the gel is to also function as a conditioner such ingredients as protein derivatives, silicone derivatives, or quaternary ammonium compounds must be added as well. A typical hair gel formulation is given in Table 1 below.
What is described herein is a composition having a unique rheological and viscosity synergy between blends of the defined terpolymer and copolymer. These associative polymers have hydrophobic moieties along their hydrophilic backbone which form inter- and intra-molecular linkages. This network increases viscosity above that due to just the mechanism of chain entanglement alone. The theoretical mechanism of action is that both associative polymers form a network with themselves to promote a unique viscosity enhancement in personal care products such as hair gels. This synergistic effect allows for low levels of the polymers in hair care compositions without affecting other attributes of the physical properties of the product or its performance on the hair. Although hair care gels are emphasized in this invention, efficacious gels using the synergistic composition of the invention can be produced also for skin care, such as eye gel products.
Acrylidones are a line of products that are based on the copolymerization of vinylpyrrolidone and acrylic acid. One derivative of such chemistry is a terpolymer of a PVP/acrylate copolymer which is hydrophobically modified with C12 groups, i.e. a polyvinylpyrrolidone/acrylic acid/lauryl methacrylate terpolymer (Formula 1), (referred to herein after as xe2x80x9cTERPOLYMERxe2x80x9d). This terpolymer is available in a wide range of monomer ratios typically 20-90 wt. % VP, 1-55 wt. % AA and 1-25 wt. % LM. Preferably the terpolymer has about 50-75% VP, 15-30% M and 5-15% LM. The acrylic acid portion can be neutralized with an alkaline earth base such as sodium hydroxide or an organic amine such as aminomethylpropanol. The degree of neutralization, based on the acrylic acid portion of the terpolymer, can range from 10 to 100%. 
Thickeners most typically used in hair styling gels are Carbomers, cellulose derivatives such as hydroxyethyl cellulose HEC, PVM/MA decadiene crosspolymer, and acrylates/steareth-20 methacrylate copolymer.
Aculyn(copyright) 28 from Rohm and Haas is an Acrylates/Beheneth-25 Methacrylate Copolymer (referred to hereinafter as xe2x80x9cCOPOLYMERxe2x80x9d), is a thickener/stabilizer having the structure shown in (Formula 2). It is supplied as a milky white, 20% solids aqueous solution at pH 3.0+/xe2x88x920.5. Thickening is immediate when neutralized with a suitable base. It also is a hydrophobically modified alkali soluble emulsion (HASE) and it thickens by two distinct mechanisms: (1) charge induced polyelectrolytic chain expansion and (2) association of alkyl groups. 